The present invention relates to coping saws and, more particularly, to power driven coping saws. A typical coping saw includes a thin, linear saw blade held under tension in a U-shaped frame having a handle extending away from and generally parallel to the saw blade. To cut a work piece, such as wood, the saw blade is manually pushed and pulled in reciprocating directions. Occasionally, the blade of the coping saw is bent or broken when the blade is unable to cut through the work piece and is jammed or caught. The blade of the coping saw is especially susceptible to bending or breaking when pushed through the work piece. In commercial settings, manual cutting with a coping saw is highly labor intensive, time consuming, and prone to produce repetition-induced injury. Thus, there is a need for a hand-held powered coping saw. To overcome the shortcomings of manual coping saws, the blade of the powered coping saw must be held taut and pulled, not pushed, with equal force in each direction through a work piece to prevent the blade from jamming, bending, or breaking.
Powered coping saws disclosed in prior patents have attempted to perfect a design which pulls the blade with equal force in opposite directions through the work piece; however, for various reasons these saws have not proven practical. For example, U.S. Pat. No. 4,949,464 issued on Aug. 21, 1990 to Adomatis discloses a battery operated coping saw including motor means attached to one end of a saw blade and spring means attached to the opposite end of the saw blade. To reciprocate the saw blade, the motor means pulls the blade in a first direction toward the motor and, thereafter, the spring means pulls the blade in a second direction away from the motor. As claimed, the spring means must operate to pull the blade in the second direction away from the motor but yield to allow the motor means to pull the blade in the first direction toward the motor. As a result, the motor means and the spring means can not pull the blade with equal force through the work piece thereby making the blade susceptible to jamming or breaking when the blade is pulled by the spring means in the second direction away from the motor.
U.S. Pat. No. 5,369,887 issued on Dec. 6, 1994 to Keevers also discloses a powered coping saw. The saw includes a motor means which drives a reciprocating linkage attached to opposite ends of a saw blade. The reciprocating linkage is comprised of three arms and pivots to pull the saw blade in opposite directions. Although the reciprocating linkage pulls the blade with equal force in opposite directions, the design has several shortcomings. Foremost, the arms are heavy and linked in a complicated and expensive arrangement. Accordingly, there is a need for a powered coping saw which overcomes these shortcomings in the prior art.